SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Aren't tree roots fun? When the constriction is between heads, it is more obvious. No easy cure but to install more pipe.

Problem fixed! I replaced the valve - not the problem - did not think it was, but thougth it was an easy enough to try. I purchases a 100' roll of 1" poly and bypassed the inground line between the valve and the 1" line near the hose bib I mentioned in previous replies above. The sprinklers worked perfectly. The problem was an obstruction in that line. Now to fix. The line is a 1" poly that was already installed long before I purchased this home so I did not know where it was buried (and it was buried deep). As far as I could tell it went very near two pine trees we had planted about seven years ago so I suspected a root had collapsed the line. Too many roots to dig around to find the original pipe so I dug a new ditch away from the trees and ran a new 1" PVC line. Works great now! Thanks to all those who offered opinions.

Why would the city water supply be able to match the pump? They almost never do. You have stated that there are absolutely no leaks anywhere in the zone, and no one is doubting your word. All that remains is the control valve. Or there might be a constriction in the line between the control valve and the first head. Tree roots? Multiple pressure gauge readings might isolate an area where pressure loss is happening.

Thanks for the suggestions. I will replace the valve. BUT - what explains the lack of pressure (input 75 PSI) when directly connected to city water with the connection of the city water directly to one of the heads? The valve is not even in the circuit.

I am with Wet Boots on this one, especially with a valve of that age and it having a metering rod (the metal rod). Over the years of use the metal rubs away when the diaphragm opens and closes. This will cause irregular valve operations. The best thing to do is a COMPLETE valve replacement. I also feel it may be in your best interest to start thinking about the others as well. I would assume they will fail with the same symptoms as this one did. Incidentally, most manufactures of valves abandoned that design for that very reason. They valve would fail due to wear on the metering rod or the orifice inside the metering tube of the diaphragm. This would allow water to flow to the top side of the diaphragm faster than it can be bled off through the solenoid. Just remember this while picking out a new valve. If you stick with a Rain-Bird or Hunter valve you will do fine.

Replace the valve, <b>the entire valve</b>, if you don't know how to clear the internal passageways in the valve body. This seems to be the only remedy you haven't tried.

Getting wierder! The valve has a "bleed valve" on top, a long thin metal shaft that goes down the center of the valve with a plastic knob on top. By turning this 1/2 turn you can operate the valve manually. The top of the valve is a faucet type handle so you can turn the valve on manually and adjust the flow just as one would on a faucet. I have the same problem if I use the valve fully open manually and using the system with the automatic timer.


Now for the wierd= I installed a hose bib about 3/4 way between the valve and the first head when I originally installed the system. This is where I have been taking pressure readings. I have connected city water, 75 PSI, to this faucet and turned on full. The connection is thru a 1/2" line. Not enough pressure to raise the heads. I then removed the head at the END of one of the two lines in this zone and connected city water. Again, not enough pressure to raise the heads. So I have fed 75 PSI water from both ends of this line with no pressure getting to the heads! I know I do not have a leak as after two days the lines were still full of water. The heads are about six feet higher than the pump, so no drain back. Ideas? I think I will remove all the heads and flush the system with city water and 120 PSI air from my compressor. Thanks for any suggestions..

I am unfamiliar with that model of valve. Does it have a metal rod that goes down the center of the diaphragm from the top to the bottom of the valve?

This valve and all the valves in the system are: Toro 1" Model 53381. I installed the system 8 years ago.

It is still not out of the realm of possibility for a partial blockage to exist in the body of the valve, where flow of 'control' water is opened and closed by the solenoid. The right sort of partial blockage will produce the phenomenon you describe.